Indexing device for welding machines



March 22, 1949. A. M. UNGER INDEXING DEVICE FOR WELDING MACHINES 2 Sheets-Sheet l A. M. UNGER INDEXING DEVICE FOR WELDING MACHINES Filed March 31, 1947 v 2 Sheets-Sheet 2 Patented Mar. 22, 1949 INDEXING DEVICE FOR WELDING MACHINES Arthur M. Unger, Chicago, Ill., assignor to Pullman-Standard Car Manufacturing Company, Chicago, Ill., a corporation of Delaware Application March 31, 1947, Serial No. 738,469

6 claims. l

This invention relates to electric welding machines, and more particularly to an improved device for successively indexing the work holding table of such a machine to pre-determined welding positions and for otherwise controlling machine operation.

The principal object of the invention is to provide an indexing device of this character that has universal application, that is, `a device capable of use with all welding problems to which the Welding machine itself is suited. In brief, the invention eliminates the need for providing a separate indexing device for each work problem, and thus eliminates the expense of constructing a plurality of such devices. It also eliminates a storage problem such as would be occasioned by the use of a large number of individual indexing devices.

For a better understanding of the importance of the invention, a welding machine and the nature of the work with which the machine is normally used will be described hereinafter.

By way of general introduction, the welding machine with which the invention is used has a large work holding table that is mounted for longitudinal movement on a fixed base. A transverse row of spaced welding electrodes is disposed above the table centrally of the base. The table is adapted for movement to successive pre-determined positions (called index points) with respect to the electrodes, at which positions the electrodes descend upon the work and accomplish the desired welding. 'I'he present invention concerns itself with an improved device that co-operates with the machine and controls its operations.

Other objects and advantages and the nature of the invention will become apparent as the description proceeds, reference being had to the accompanying drawings wherein a preferred form of the invention is shown. It is to be understood that the description and drawings are illustrative only, and are not to be taken as limiting the invention except insofar as it is limited by the claims.

In the drawings:

Fig. l is a perspective View, shown somewhat diagrammatically, of a welding machine embodying the invention;

Fig. 2 is a fragmentary sectional view generally on line 2--2 of Fig. i;

Fig. 3 is a fragmentary plane view of the improved indexing device, and

Fig. 4 is a diagrammatic view of the basic components of the welding machine showing the relationship of the invention thereto.

As shown in Fig. l, the welding machine herein has a large work holding table Ill. The top of the table may be covered with a continuous metal plate so that a durable work holding surface is provided, the surface lying in a flat plane.

The table top may also function as a conductor in the electrode circuit system.

Table lil is slidably mounted for longitudinal movement on a base I I by means of a plurality of rollers I2 which ride on spaced rails I3. Racks I depend from table Ill into engagement Withcooperating gear wheels I5 which are driven through a suitable power train I6 by a table motor Il.

Midway along the length of base II a superstructure 20 is provided, the superstructure including side uprights 2| and 22. A transverse member 23 extends between the tops of uprights 2l and. 22 and is rigidly connected thereto. Below transverse member 23 is disposed a transverse beam 24, the ends of beam 24 being in vertically slidable engagement with uprights 2| and 22. A plurality of links 25 and 26 have one end thereof pivoted respectively to transverse member 23 and beam 24, the other ends of the links being pivoted together in the well-known manner to provide a toggle arrangement. A toggle actuating element 2i forms a mechanical connection between the various common pivot points of the respective sets of links 25 and 26. As will be understood, transverse movement of actuating element 2l effects vertical motion of beam 24.

The beam 24 carries a plurality of spaced vertically disposed welding electrodes 30, each electrode being provided with a spring 3l that is capable of maintaining downward pressure on the electrode tip when the electrodes are brought in contact with the work, as more fully described hereinafter.

rIoggle actuating element 21 may be transversely moved in any suitable manner such as by a hydraulic system generally shown at 35. Such a system has a motor 36 and associated pump 31, the pipes 38 and 39 from the pump leading to a solenoid valve assembly 49.

The valve assembly ll is operatively connected to a cylinder 4I, the cylinder containing two aligned pistons (not shown), a main piston for actuating elem-ent 2l and a secondary piston that is movable to permit an extended or retracted" stroke by the main piston. Thus, the main piston is capable of strokes of two lengths. First, it has a stroke from one extreme position (Where beam 26 is in its lowermost position and electrodes'BI) are in contact with the work) to a normal position where the electrodes 30 are raised a short distance above the work. Second, it has a stroke from the same extreme position to a retracted position where the electrodes are raised to an uppermost height so that the electrodes may clear obstacles present on the work table.

Side upright 22 carries a lower limit switch 45, a normal limit switch '45 and a retracted limit switch 4l, the first named two being actuated by .numbered iii, 8,2, 83 and 8d (Fig. 3).

a plate all carried by movable beam 2li and the latter beingv actuated-by a pin ifi on beam 2d. The functionv of these limit switches and associa-ted actuating elements will be discussed hereinafter.

Side upright 2i carries a` pair of spaced plates, an upper plate 5c and a lower plate iii, the two plates extending from upright 2l toward table iii. Referring to Fig. 2, upper plate 5t ycarries a plurality of (four in the example shown) photo-electric means 52, while lower plate 5i carries a like number of cooperating aligned illurninationy sources 53. The respective photoelectric means-illumination source combinations are connected in circuits that control the op- `eratingcycles of the welding machine in a manner hereinafter described.

"Referring now to Fig. 4,the essential electrical and mechanical components of the above described welding machine are shown in somewhat lsimplified form. 'Electric power is led from the line' 5cl through a starting switch 55 to .the variouscontrol circuits diagrammatically shown at 56. Connected to control circuits 5t is a left- `right switch' el that is suitably pre-set to detern `mine the left or right movement of table i'; The table motor I7 is operatively connected to conn trol circuits 55 so as to be responsive to the posi- 'tion of left-right switch 51.

pairs to ythe secondary Gil of respective trans- -formersiL the primaries `ci! of the transformers being connected to control circuits 5t by means lof conductors 19.

' The indexing device of 'thezpresent invention .comprises a templatel associated with table l `and lextending 'substantially throughout .its

.=length,f;the template beingdisposed between the spaced plates t and 5i carried by side upright As best shown in Figs. '2 and 3, the template may take ythe form of an angle member having leg, f75 lying betweenplates 5l! and 5i, `and leg v'l lfixed yto the side of table In in any suitable manner; as by bolts il. Leg l5 forms the'effective .-fporitionpof the indexing devices, and this portion together with its function in connection with the welding machine will now be described.

" The leg .15, Vhereinafter called the template, is

perforated, withv a .plurality o1"v spaced `longitudinal rows of spaced holes, the rows shown being venience, the rows will bev referred to as rows I, 2, s and Il,.- respectively. In practice, the holes .may be about a quarter of an inch `in diameter, :andalong alongitudinal Arow they may be spaced Aon three-eighth .inch centers, thus to provide'for a sumciently large number of .index points. The transverse spacing between rows, of course, is determined bythe transverse spacing of photo- .electricmeansxEL each row of holes vlyingfcn va Alinebetween aphoto-electric, means and its asso- Aciated illumination source.

Means .are provided in connection with the template for separately closing and opening the holes to the passage of light. Any suitable means may be.used,v but I have found it convenient to` .employ-simple rivets such as shown at 85 in Fig,

2. In thatiigure it will be noted that rivets 85 are shown inthe illustrated holes of rows l :tand 4,. butthat no rivet :isshown-in .the hole lof row 2. "..Thus :lightis permitted to; passLfrom .illumi- For conl. Liu

:machine d sbeets or sl nation source 5t through the open hole in row 2 to the aligned photo-electric means 52, This passage of light excites the photo-electric means and controls certain steps in the cycle of the welding machine, as will be hereinafter described.

Holes lying in rows i and 2 of the template effect the stopping of table motor il when the motor has moved the table to a pre-determined 'index point as established by the absence ci a vvents an abrupt halt in the table movement, and

that coasting thus occurs when the circuit associated with either row i or row 2 deenergizes 'table motor il. This coasting may be compensated for either by having the position. of plates il@ and tivi staggered with respect to the plane ci the welding electrodes tl, or, if the plates and the electrodes are in alignment, by taking this kcoasting into account when removing rivets from the template.

Holes lying in rows 3 and d respectively cooperate with rows l and 2, that is, the holesin row t are effective when table i@ is moving to the right, and the holes in row c are effective when the table is moving to the left. The holes in rows 3 and Il are opened to the passage ci light to actuate circuits which permit the hydraulic system to go to its retracted position, thus tol raise electrodes Si) to their uppermost height so as to clear obstacles present on the table.

Prior the acti bed tJ work te w.

well adapte Sie piace upon i iorrn the ente cars. When used purpose it is necessary to .re-enforce the vto this end rigi. y associating the corrugated stiffeners 9i to the a welded joint being provided paced intervals along each trough of a corru- .gated stiffener.

. The present welding machine with its plurality of electrodes is adapted to simultaneously pro vide a welded. joint in each trough along transverse line across the stiffener. At the conclusion ci, one transverse line ci Welding, the electrodes are raised from the work. and table ill then moves to b t, work to the following index point for the next transverse line of welding. Thus it can be seen that by the use ci this machine a complete railroad car side can have its side sheets and corr gated stiieners welded together in a .rapidand .eiiicient manner. The operating cycle of the welding machine and its cooperation with the indexing device will now be described.

Assuming that the work has been carefully :irren -d en table iii, the template of the indexing device is set to control machine operation in accordance with the requirements of the To this end, the operator removes rivets rcws i and 2 so 'that table lil will stop the ,proper pre-determined index points iorthe appli .cation of welds to the work. It will be reniem- .bererl that row i .controls vtable movement to the right, while row 2 controls table movement to the left. Where a large number of railroad cars of the same type are being made, it is desirable to set the template for both directions of table movementl so that machine operation may be substantially continuous, interruptions occurring only when the table reaches its limits of movement so that the completed Work may be removed and new work added. In the event the work has so-called obstacles thereon that may not pass under the electrodes when the electrodes are at normal height, rivets are removed from rows 3 and 4 at the appropriate places to cause the electrodes to raise to their retracted height, thus to clear the obstacles.

When the work has been arranged on the table and the template set for desired machine operation, the switch 'l should be set to its left or right position dei. ng upon the iirst direction of table travel desired. Thereafter starting switch is actuated assuming table I is not then at an index point, motor ll is energized to start table movemei in the direction determined by switch 5l. flssurrline the table is moving to the left, movement continues until an open hole in row 2 admits the passage oi light from illuminating source 53 to corresponding photo-electric means 5'2. The circuit associated with this photoelectric means deenergizes table motor Il', although, as mentioned, the table coasts a distance beyond this point to the precise index point desired. Electrodes Sil are disposed above the work either at their normal or retracted height.

The motor stopping circuit actuates a rst valve in the solenoid valve assembly 40 of the hydraulic system to send the main piston in cylinder to an extreme position in one direction whereby the toggle mechanism lowers electrof fb '1o contact with the work. Springs 3l on the individual electrodes maintain suitable pressure between the electrodes and the work.

When the electrodes 3i) reach their Work contacting position, plate t8 carried on beam 24 actuates lower limit switch l5 to establish a circuit which energizes electrodes 30. A time delay relay device (not shown) automatically deenergizes this circuit after a pre-determined time to remove the current 4from the electrodes. The time delag.7 relay may also provide for a short hold time after the circuit has been broken so that the worl; may cool under pressure.

This time delay relay then energizes a circuit to actuate a second valve in solenoid valve assembly lo that the piston returns to its normal position and thus raises electrodes 38 to their normal height above the work. At this point, the top of plate actuates normal limit switch i6 to energize a circuit that starts table motor li which then. moves table lo to the left until the next open hole in row 2 admits light to photoelectric means 52. Thus successive cycles of machine operation occur over the limit of left direction travel of table lil.

A variation in the above described cycle occurs v-,fhen obstacles are pfesent on the work and it is desired to raise electrodes 3D to their retracted height to clear such obstacles. The position of such obstacles is, of course, accounted for in the setting of the holes in rows 3 and 4, row 4 being effective when table i@ is moving to the left. Assuming there is an obstacle between the present index point and the following index point, the hole in row l in alignment with its associated photo-electric means at the present index point is left open to permit the passage of light. The

i problems.

excited photo-electric means actuates a circuit which renders the normal limit switch 46 inoperative.

circuit also actuates a third valve of the solenoid valve assembly @il which retracts the secondary piston in cylinder lil. This has the effect of permitting an increased stroke of the main piston whereby the electrodes are raised to their retracted height. At this point retracted limit switch lll is actuated by pin 49 to start table motor il, and table motion continues until table l is moved to the next index point. When the light through the open hole in row 4 is cut 01T (by table motion) from cooperating photo-electric means the circuit associated therewith actuates the third valve oi solenoid valve assembly Llil to return the secondary piston to its normal position.

A suitable automatic switch (not shown) may be employed to eiect a Final stop when table Ill arrives at its extreme limit of travel in either direction. As mentioned, at the end of table travel in one direction the work may be removed from the table and replaced with new work. Thereupon the machine will respond to the settings of the other two rows of holes in the indexing device and will go through the prede-termined cycles with the table moving in the opposite direction.

Thus it will be seen that the indexing device of the present invention greatly enhances the usefulness of a welding machine of this character, and it eliminates the expense of constructing separate templates for each particular welding job. Since such a machine would normally be used for a large number of different jobs, it can be seen that the construction of a separate template for each job and the matter of storing such templates for future use would be major The present invention completely eliminates such `problems through the use of a single permanently attached template which may easily be set by the operator for each particular job.

While four longitudinal rows of holes have been shown in template l5, useful results -m-ay be obtained by using only two rows. In this case the plates 5t and 5l that support the photo-electric means and illumination sources, respectively, would be slidably mounted so they could be adjusted back and forth to compensate for table coasting. Thus only two photo-electric meansilluminating source combinations, need be -provided.

From the above description it is thought that .the construction and advantages of the invention will be readily apparent to those skilled in the art. Various changes and modifications may be made without departing from the spirit or losing the advantages of the invention.

Having thus described `the invention, what I claim as new and desire lto secure by Letters Patent is:

1. In a welding machine having the following: a table for holding work; means for moving said table to extreme 4positions in both longitudinal directions; a support disposed transversely above said table; spaced electrodes depending from said support; means for moving said electrodes selectively to positions (l) where said electrodes contact the work, (2) where said electrodes are disposed a normal height above said work, and (3) where said electrodes are disposed a retracted height above said work whereby said electrodes may clear obstacles on the moving table; and

control circuits for actuating (1) said table movingA means, (2) said support moving means, and (3) the current to said electrodes; said control circuits including illumination sources and aligned photo-electric means cooperating respectively with each source; the combination therewith of an indexing template associated with said table and extending the length thereof and disposed between said illumination sources and aligned, cooperating photo-electric means, said indexing template vhaving four spaced rows of spaced holes therethrough, each row being in alignment with an illumination source photo-'electric means, two of said rows being effective to control machine operation during table motion in one direction and the other two of said rows being effective during table motion in the opposite direction, and means associated with said holes selectively to block the passage of light therethrough and to admit the passage of light, the holes of one row oi each set of two being opened to admit the passage of light at Ipredetermined index points to stop table motion, the holes of the other row of each set being opened .to admit the passage of light whereby the electrodes are raised to a retracted height above the work, thus to provide an indexing template suitable for use with a plurality of work problems.

2. In a welding machine having the following:

a table for holding work; means for moving said table to extreme positions .in both longitudinal directions; a suppe 1t disposed transversely above said table; spaced electrodes depending from said support; means for moving said electrodes selectively to positions (l) where said electrodes contact the work, (FZ) where said electrodes are disposed a normal height above said work, and (E) where said electrodes are disposed a retracted height above said work whereby said electrodes may clear obstacles on the moving table; and control circuits for actuating (l) said table moving means, (2) said support moving means, and (3) the current to said electrodes; said control circuits inciu .g illumination sources and aligned photo-electric means cooperating respectively with each source; the combination therewith of an i dering template associated with said table and e the length thereof and disposed between said illumination sources and aligned, cooperating photo-electric means, ind ig tempiate having a longitudinal row or" spaced holes therethrough in alignment 'with each and means associated with said holes selectively to block the passage of light therethrough and to admit the passage oi light, said means being positioned to admit the passage of light through holes at predetermined index points along said table as required by particular wort; to elfi/ect machine operation in response 'to a particular setting oi said indexing template, thus to provide indexing template suitable -for use with `a plurality of work problems.

3. In a welding machine having the following: a work holding table; means for moving said table in a progressive manner; a support disposed transversely above said table; spaced electrodes depending from said support; means for moving said electrodes selectively to positions (l) where said electrodes contact the work and (2) where said electrodes are disposed above said work; and control circuits for actuating said table moving means and said electrode moving means; said control circuits including an illumination source Lib and aligned photo-electric means; the combination therewith of `an indexing template extending the length of said table and disposed between said illumination source and said photo-electric means, said indexing template having a longitudinal row of spaced holes in alignment with said source-means, and means associated with said holes selectively to block the passage of light therethrough and to admit the passage of light, said means being positioned to admit the passage oi light through holes at pre-determined index points along said table to stop said table moving means, to lower the electrodes to the work, to energize and deenergize said electrodes, to raise said electrodes and to start said table moving means, thus to provide an indexing template suitable for use with a plurality of work problems.

4. In a welding machine having a movable Work holding table, welding electrodes thereabove, means for progressively moving said table, means for controlling said table moving means, said controlling means including a circuit associated with said table moving means and having cooperating piloto-electric means and an illumination source; an indexing template extending the length of said table and disposed between said photo-electric means and said illumination source, said template having a row of spaced holes throughout its length, means for closing said holes to the passage of light which on removal permit light to pass from said source to said photo-electric means and thus stop operation of said table moving means.

5. In a welding machine oi the character described, a work holding table, means for progressively advancing said table to a plurality of predetermined index points, said means including an indexing template extending the length of said table, said template having spaced holes throughout its length, removable means for selectively closing the individual holes to the passage of light, and photo-electric means operatively associated with said holes and With said table advancing means whereby said table is stopped in response to open holes in said template.

6. In a welding machine of the character described, a work holding table, means for transversely advancing said table to a plurality 0f predetermined index points, said means including an indexing template substantially coextensive with the length of the table and having spaced lengthwise thereof light transparent portions that permit passage of light therethrough, removable means for selectively closing to the passage of light each of said light transparent portions, and photo-electric means operatively associated with said light transparent portions and with said table advancing means whereby said table is stopped in response to open light transparent portions in said template.

ARTHUR M. UNGER,

CITED The iollowing references are of record in the iile of this pai nt: 

